1) Field of the Invention
This invention relates to electrochemical batteries, and more particularly to an improved argentic oxide bipolar electrode for use in an electrochemical battery for marine use of improved reliability.
(2) Description of the Prior Art
Battery requirements for marine data systems vary from a few milliwatts for CMOS instrumentation to several tens of kilowatts for the operation of a mini autonomous underwater vehicle (AUv). Nonaqueous lithium cells and zinc-based primary cells, as well as nickel-cadmium and lead-acid batteries, are currently used. Safety and the corrosive nature of the electrolyte and/or some cathode materials used in such power sources dictate that cells and batteries be well sealed to prevent leakage and/or rupture during storage and use. Lithium batteries use hermetic seals with safety vents and a fuse. Alkaline cells are rendered leakproof by suitable double crimp joints. Lead-acid cells use a gelled electrolyte to prevent spillage of the electrolyte. Such techniques have minimized the hazards of handling and use, however at the expense of the costs. Sealed cells require a "pressure hull" enclosure for deep sea application and thus use of a pressure hull significantly reduces energy density and concomitantly increases usage cost. Other types of power cells used in undersea applications are water activated magnesium batteries with a bipolar configuration as open cells. A magnesium anode and a metal halide-based cathode allows the use of sea water as the electrolyte and do not require a pressure hull housing for deep sea applications.
Deferred actuated batteries, such as silver chloride-magnesium batteries using sea water as an electrolyte have been used for years, and are expensive being based upon the use of a precious metal, i.e. silver.
Aluminum-silver oxide batteries for use in electric torpedoes include bipolar electrodes formed of an aluminum alloy plate, a silver foil and an electroformed silver oxide layer containing a silver grid with silver in the argentous ionic form. Fabrication of such bipolar electrode and assembly into a battery configuration is cumbersome, costly and exceedingly unreliable due to the use of tape to hold together the bipolar electrode. There are requirements for high energy and high power density with concomitant depth independency.
In U.S. Pat. No. 4,910,104 to Rao et al. and assigned to the same assignee as the present invention, there is described a deferred actuated battery assembly for seawater activation.